The Design And Optimization Of DC/DC Converters In Single Phase Grid-Connected Photovoltaic System

In the face of resources exhaustion of today, solar energy attracts more and more attention of the international world as a clean and renewable energy resource. In recent years, the grid-connected photovoltaic system has been developed dramatically and it has become one of the main methods in solar energy utilization.This thesis mainly researches regulative photovoltaic grid-connected system. Because of the energy storage link in regulative photovoltaic grid-connected system, it needs some DC/DC converters to meet the different voltage convert situations.The main contents of this thesis are listed as follows:(1) In the basic analysis of DC/DC converters suited for this situation, the design procedures of common Boost converter are given in this thesis. The 100 Hz low frequency ripple caused by the single phase inverter is analyzed and the average current mode control method is used to minimize the effect caused by the 100 Hz low frequency ripple.(2) Based on the analysis of the shortage of the single-phase Boost converter in high step-up applications, this thesis describes a type of Boost converter using coupled inductor to extend the voltage gain. And also a method of adding an Equivalent DC Voltage Source in the output side of non-isolation converters which can extend the step-up voltage gain is proposed in this thesis.(3) The different types of battery and charging methods suited in regulative photovoltaic grid-connected system are introduced in this thesis. The detailed design procedures of 540W constant current and constant voltage charger are presentedfinally.